Extract filesmap to own file

filesmap.go

@@ -0,0 +1,67 @@
+package main
+
+import "os"
+
+// FilesMap is a struct for listing files by Size and Hash to search for duplicates
+type FilesMap struct {
+	FilesBySize map[int64]map[string][]string
+}
+
+// Add a file to the Map and calculate hash on demand
+func (fm *FilesMap) Add(path string, info os.FileInfo) error {
+	if info.IsDir() {
+		return nil
+	}
+
+	fileInfo := path
+
+	filesByHash := fm.FilesBySize[info.Size()]
+
+	// first file with same size
+	// => create new map for size
+	if filesByHash == nil {
+		filesByHash = map[string][]string{}
+		fm.FilesBySize[info.Size()] = filesByHash
+		filesByHash[""] = []string{fileInfo}
+		return nil
+	}
+
+	// second file with same size
+	// => calculate hashes for all entries
+	if _, hasEmptyHash := filesByHash[""]; hasEmptyHash {
+		err := appendByFileHash(filesByHash, fileInfo)
+		err2 := appendByFileHash(filesByHash, filesByHash[""][0])
+
+		delete(filesByHash, "")
+
+		if err != nil {
+			return err
+		}
+
+		return err2
+	}
+
+	// for later files always append by hash
+	return appendByFileHash(filesByHash, fileInfo)
+}
+
+func appendByFileHash(filesByHash map[string][]string, fileInfo string) error {
+	hash, err := calculateHash(fileInfo)
+
+	if err != nil {
+		return err
+	}
+
+	if _, ok := filesByHash[hash]; ok {
+		filesByHash[hash] = append(filesByHash[hash], fileInfo)
+	} else {
+		filesByHash[hash] = []string{fileInfo}
+	}
+	return nil
+}
+
+func newFilesMap() *FilesMap {
+	return &FilesMap{
+		FilesBySize: map[int64]map[string][]string{},
+	}
+}